Grid references and Ordnance Survey maps
Geography · Key Stage 2 · The School
Eight points, not four
North, East, South and West are the four you know. Between them sit north-east, south-east, south-west and north-west, giving eight points. Going clockwise from north the order is N, NE, E, SE, S, SW, W, NW. Directions on a map are always given from the first place to the second: from the church TO the bridge may be south-east even though the return journey is north-west.
Four figures: which square
An Ordnance Survey map is covered in a numbered grid. A FOUR-FIGURE reference names one square. Read the EASTING first — the line up the left-hand side of the square, numbered along the bottom — then the NORTHING, the line along the bottom of the square, numbered up the side. The rule people remember is: along the corridor, then up the stairs.
Six figures: where in the square
Four figures gives you a square a kilometre across, which is not much use for finding a footbridge. A SIX-FIGURE reference splits each square into ten. Estimate how many tenths across the square your feature sits and add that digit to the easting; do the same going up and add it to the northing. So the square 31 45 becomes 317456 — precise to about a hundred metres.
A church sits in the square with easting 43 and northing 27. The four-figure reference is 4327 — a one-kilometre square, and everything inside it shares that reference. Now divide that square into ten by ten. The church is 6 tenths across and 4 tenths up, so the six-figure reference is 436274. Four figures names a field; six names a building. Eastings before northings, every time.